Function compute_averages

Source/astcenc_entry.cpp:1056–1108

* @brief Compute regional averages in an image. * * This function can be called by multiple threads, but only after a single * thread calls the setup function @c init_compute_averages(). * * Results are written back into @c img->input_alpha_averages. * * @param[out] ctx The context. * @param ag The average and variance arguments created during setup. */

 * @param      ag    The average and variance arguments created during setup.
 */
static void compute_averages(
	astcenc_context& ctx,
	const avg_args &ag
) {
	pixel_region_args arg = ag.arg;
	arg.work_memory = new vfloat4[ag.work_memory_size];

	size_t size_x = ag.img_size_x;
	size_t size_y = ag.img_size_y;
	size_t size_z = ag.img_size_z;

	size_t step_xy = ag.blk_size_xy;
	size_t step_z = ag.blk_size_z;

	size_t tasks_y = (size_y + step_xy - 1) / step_xy;

	// All threads run this processing loop until there is no work remaining
	while (true)
	{
		size_t count;
		size_t base = ctx.manage_avg.get_task_assignment(16, count);
		if (!count)
		{
			break;
		}

		for (size_t i = base; i < base + count; i++)
		{
			size_t z_task = i / tasks_y;
			size_t y_task = i - (z_task * tasks_y);

			size_t z = z_task * step_z;
			size_t y = y_task * step_xy;

			arg.size_z = astc::min(step_z, size_z - z);
			arg.offset_z = z;

			arg.size_y = astc::min(step_xy, size_y - y);
			arg.offset_y = y;

			for (size_t x = 0; x < size_x; x += step_xy)
			{
				arg.size_x = astc::min(step_xy, size_x - x);
				arg.offset_x = x;
				compute_pixel_region_variance(ctx.context, arg);
			}
		}

		ctx.manage_avg.complete_task_assignment(count);
	}

	delete[] arg.work_memory;
}

#endif